Add local-mode workspace, ZIP import/export, and richer pin/ADC/serial sims

Boot:
- Editor now picks local vs server mode based on URL flag, sign-in
  state, and a stale local-mode flag. Signed-in users are no longer
  bounced to IndexedDB if they had previously clicked "Use locally".

Local mode:
- New LocalWorkspaceClient (src/static/local-workspace.js) with
  pluggable IndexedDB and File System Access backends. Picked folder
  handles persist across reloads with a Reconnect button when the
  permission lapses.
- Static-only host: scripts/serve_static_editor.py serves src/static/
  with COOP/COEP so SharedArrayBuffer-backed sims keep working.
- Bundled MicroPython stubs ship under src/static/bundled-lib/ for
  static hosting; FastAPI also exposes them at /api/public/lib-bundle.

Workspace import / export:
- Zero-dep ZIP encoder + reader (STORE + DEFLATE via
  DecompressionStream). Export/Import buttons in the workspace badge
  work in both local and server modes; imports are confined to code/.

Pin / ADC / Serial simulation:
- machine.py grows ADC, UART, expanded Pin, and PWM mocks, all driven
  by SharedArrayBuffer when cross-origin isolated and falling back to
  postMessage + [pin-out] stdout markers otherwise — pins, ADC slider,
  and serial input now keep working over plain HTTP / LAN-IP origins.
- NeoPixel pins are claimed via a [pin-claim] marker and dropped from
  the Pins panel so the data line doesn't flicker per write().
- New demos: adc_slider_demo.py, pin_demo.py, serial_demo.py.

Lib layout:
- Single source of truth at repo lib/; workspace/lib/ caching layer
  removed and the directory deleted. Filesystem service reads stubs
  directly from PROJECT_ROOT/lib.

UI:
- Home page slimmed to "Sign in" + "Use locally" with optional editor
  / manage-users links. Admin user/invite UI moved to /users.
- Workspace badge gains storage indicator, Folder…/Reconnect, Export,
  Import, and Exit controls.
- Mobile-friendly tweaks: safer-area padding, larger touch targets,
  iOS-zoom-proof serial input, file-tree highlight fix.

Tests:
- test_auth.py patches PROJECT_ROOT for the lib-shared test so the
  repo-root lib refactor stays green. test_api.py asserts the new
  "LED Editor" branding.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_auth.py

@@ -18,7 +18,7 @@ def _reload_app(tmp_path, monkeypatch, **env):
     monkeypatch.delenv("BOOTSTRAP_ADMIN_PASSWORD", raising=False)
     for k, v in env.items():
         monkeypatch.setenv(k, v)
-    config.WORKSPACE_ROOT = tmp_path
+    monkeypatch.setattr(config, "WORKSPACE_ROOT", tmp_path)
     db_sess.reset_engine()
     importlib.reload(main)
     return main.app
@@ -304,9 +304,23 @@ def test_users_have_isolated_workspaces(tmp_path, monkeypatch):
 
 
 def test_lib_is_shared_read_only_across_users(tmp_path, monkeypatch):
+    """`lib/` lives at the repo root (single source of truth), not under WORKSPACE_ROOT,
+    so we patch `config.PROJECT_ROOT` to give the test its own isolated lib bundle."""
+    import editor_app.config as config
+
     shared_lib = tmp_path / "lib"
     shared_lib.mkdir(parents=True, exist_ok=True)
     (shared_lib / "shared.py").write_text("VALUE = 42\n", encoding="utf-8")
+    # Mirror canonical demo files so `_seed_canonical_demos_into_code` still works.
+    real_demos = config.PROJECT_ROOT / "workspace" / "code"
+    fake_demos = tmp_path / "workspace" / "code"
+    fake_demos.mkdir(parents=True, exist_ok=True)
+    for fname in ("pattern_rainbow_demo.py", "pattern_twinkle_demo.py", "pattern_chase_demo.py"):
+        src = real_demos / fname
+        if src.is_file():
+            (fake_demos / fname).write_text(src.read_text(encoding="utf-8"), encoding="utf-8")
+
+    monkeypatch.setattr(config, "PROJECT_ROOT", tmp_path)
 
     with TestClient(
         _reload_app(tmp_path, monkeypatch, AUTH_ENABLED="true", AUTH_REGISTER_OPEN="true")